Table 4.

Detection results of the multiplex real-time PCR on the spiked food samples that inoculated with different concentations of E. coli O157:H7 and enriched with different incubation time

Target gene	Food matrice	Incubation time (h)
	CFU/gram	0	4		8		12		24
	Beef		CT a	±SD	CT	±SD	CT	±SD	CT	±SD
Z3276	80	UDb	34.50	0.29	28.43	0.07	27.98	0.10	27.98	0.10
	800	UD	30.51	0.38	24.54	0.10	24.00	0.04	24.00	0.04
stx1	80	UD	27.54	0.19	21.73	0.22	20.84	0.25	19.06	0.36
	800	UD	24.45	0.22	18.51	0.14	17.46	0.03	18.48	0.02
stx2	80	UD	31.34	0.10	25.47	0.02	25.03	0.04	23.63	0.02
	800	UD	27.93	0.34	21.68	0.03	21.33	0.06	22.52	0.05
IAC	200 copiesc	28.88	27.72		21.96		21.09		19.59
	Spinach		CT	±SD	CT	±SD	CT	±SD	CT	±SD
Z3276	80	UD	33.92	0.04	24.32	0.26	22.86	0.15	24.26	0.09
	800	UD	30.91	0.05	23.04	0.11	23.08	0.08	23.12	0.07
stx1	80	UD	27.63	0.16	17.32	0.15	15.74	0.13	16.87	0.11
	800	UD	25.04	0.06	16.57	0.12	16.25	0.15	16.37	0.10
stx2	80	UD	30.88	0.06	21.21	0.07	20.10	0.06	21.64	0.07
	800	UD	28.19	0.14	20.05	0.15	20.58	0.05	20.74	0.04
IAC	200 copies	24.94	23.82		24.77		23.83		23.69

^aData were shown as average of two independent experiment

^bUD refers to "Underdetermined", a negative detection result

^cAbout 200 copies of pUC19 plasmid DNA was added as template for IAC to each multiplex real-time PCR reaction